WO1996007833A1

WO1996007833A1 - Drum brake

Info

Publication number: WO1996007833A1
Application number: PCT/JP1995/001744
Authority: WO
Inventors: Shinichi Tanaka; Shigeru Tanaka; Teizo Shimorura
Original assignee: Hino Jidosha Kogyo Kabushiki Kaisha
Priority date: 1994-09-02
Filing date: 1995-09-01
Publication date: 1996-03-14
Also published as: EP0727591B1; US5887686A; CN1134741A; EP0727591A4; KR960706029A; DE69516393T2; CN1075607C; KR100395821B1; EP0727591A1; CA2174088A1; DE69516393D1

Abstract

This invention effectively reduces the screeching (unpleasant sound) of a brake occurring when an automobile is braked. A rod is set up on the inner surface of a rim to which a brake lining is attached, and a weight is fixed to this rod via an elastic member. Since a weight is fixed to a brake shoe via an elastic member, the weight receives the vibration of the brake shoe and is vibrated. The vibration of the weight has a low frequency and a phase equal to that of the vibration of the brake shoe. However, as the vibration frequency of the brake shoe increases, the vibration phase of the weight deviates from that of the brake shoe. At a frequency in the vicinity of a certain level and not lower than the same, a phase difference becomes substantially 180°. If this frequency is set in agreement with that of a screeching sound of the brake, the vibration of the brake shoe can be suppressed by that of the weight. It is possible to reduce the screeching sound of a brake of a large-sized vehicle, in which the size of a brake shoe is large, to a practically sufficient level by merely adding an inexpensive part to the brake, and maintain the original performance of the brake even when the brake lining is replaced.

Description

Description Drum brake

〔Technical field〕

INDUSTRIAL APPLICATION This invention is utilized for the brake of a motor vehicle. The present invention is used for a drum brake. The present invention relates to a technique for reducing so-called “brake squeal” generated when a vehicle is braked.

(Background technology)

Many studies and proposals have been made in the past to reduce brake squeaks (unpleasant sounds called "keys") generated when braking a car. The applicant has long pursued this problem.

The technique disclosed in Japanese Patent Application Laid-Open No. 3-288880 is a prior application of the present applicant, and in order to suppress vibration of the brake shoe, a friction member is provided on the inner surface of the rim of the brake shoe. A holding member is attached. The technology disclosed in Japanese Patent Application Laid-Open No. H6-16494 is an even older technology, which is also a prior application of the applicant of the present invention, and has a friction member attached to the inner surface of a rim. .

The technology disclosed in Japanese Utility Model Laid-Open Publication No. 3-8 4 4 3 6 is a utility model registration application also based on the applicant's earlier application, which suppresses the vibration of the brake shoe by attaching a weight to the inner surface of the rim. Is what you do. At the time of disclosure of this technology, there was no notice of interposing an elastic member in the weight.

Analysis and explanation of the phenomenon of brake squeal described in the above-mentioned Japanese Patent Application Laid-Open No. 3-288080, particularly the phenomenon described in FIG. Is explained to be correct in subsequent experimental studies. In other words, the main cause of the brake squeal is generated by the vibration of the brake shoe, and the force of the brake also oscillates in the radial direction as shown by the broken line in Fig. 27. I know that The technology described above has improved brake squeal, especially for small passenger cars when driving on ordinary urban roads, to a level where there is almost no practical problem. However, brake squealing still occurs depending on the conditions that are not apparent in heavy-duty vehicles, and there are still issues to be studied in their countermeasures.

The inventor of the present application observed the phenomenon of brake squeal and analyzed the observed contents in various ways. An experimental analysis was conducted on the vibration, and specific measures to suppress the vibration of the brake were examined. In the experimental analysis, we examined new methods and methods such as exaggerating the vibration on the computer screen and matching it with the frequency characteristics of the generated sound. As a result, the technology disclosed in the present application was proposed, and experiments were performed. As a result, it was proved that the technology was extremely useful as compared with conventionally known measures.

An object of the present invention is to reduce brake squeal. An object of the present invention is to provide a technique capable of reducing brake squeal in various sizes of brake shoes in the most effective form, not merely an empirical shape. An object of the present invention is to reduce brake squeal in a large vehicle having a large brake shoe in a practically sufficient degree. An object of the present invention is to provide a technique for reducing brake squeal that does not change its performance even when the brake lining is replaced. An object of the present invention is to reduce brake squeal by using inexpensive additional parts. Further, another object of the present invention is to suppress the deterioration of the elastic body and the adhesive and the deterioration of the vibration damping function of the elastic body to improve the reliability. SUMMARY OF THE INVENTION It is an object of the present invention to provide vibration damping means capable of effectively maintaining additional components even in an environment exposed to high temperatures and severe vibration.

[Disclosure of the Invention]

The present invention is characterized in that by attaching a weight to a vibration member via an elastic body, a brake squeal generated when a vehicle is controlled is effectively reduced. The vibration member is, for example, a brake shoe that is a source of a brake squeal, and a brake drum and a back plate that resonate with the brake squeal and transmit noise to the outside. It can also be mounted on a wheel cylinder. The greatest feature of the present invention is that a weight is attached via an elastic body instead of simply attaching the weight. When a weight is attached via an elastic body, the free vibration area of the weight is expanded, and the natural vibration frequency of the weight is recognized according to the properties of the elastic body. The vibration of the vibrating member is transmitted to the weight, and the vibrating member and the weight vibrate in the same phase in a low frequency region. However, as the frequency increases, the phase of the vibration between the vibrating member and the vibration of the weight gradually shifts, and at a certain frequency or at a frequency higher than a certain frequency, the vibration of the vibrating member and the weight There is a phenomenon in which the vibrations of are out of phase. The opposite phase between the vibration of the vibrating member and the vibration of the weight is nothing but the fact that the elastic body is deformed and converts the vibration energy into heat energy to suppress the vibration of the vibration member. This is the principle of the present invention.

A first aspect of the present invention is a brake shoe, which is characterized in that a weight is attached to a rim to which a brake lining is attached via an elastic body. In other words, the greatest feature is that the weight is attached via an elastic body instead of directly attaching the weight to a member that generates vibration. More specifically, by attaching a weight via an elastic body, it is possible to effectively suppress vibration and noise near or at a higher natural frequency due to the property and weight of the elastic body. Experimentally, it is experimentally confirmed that not only the natural vibration frequency but also the frequency, not only the natural vibration frequency but also the lower frequency vibrations below it are suppressed by the phase relationship between the brake vibration and the weight vibration. Has been confirmed.

The weight may be attached directly to the rim via an elastic body, or a rod may be erected on the rim, and the weight may be attached to this rod via the elastic body. It is desirable that the weight is attached to the inner surface of the rim, the side surface of the web, or the top of the ridge. Here, the “rod” means a broad rod-shaped member, and a part generally called a “pin” is included in the “rod”.

Further, the elastic body is formed in a ring shape, and the rod has a structure in which the rod penetrates the center of the elastic body. A metal rod is used for the rod, and a ring-shaped weight is included so as to include the elastic body. Can be provided. The rod may have a cylindrical shape or a cylindrical shape. Here, the ring shape includes not only a circular section in a plane perpendicular to the axis but also a polygonal section.

Further, a support is attached to the rod, a space is provided between the support and the rod, an elastic body is provided so as to include the support, and a ring-shaped weight is included so as to include the elastic body. It can also be provided. This structure has the advantage that heat is dissipated from the space between the support and the rod. In addition, if a concave portion is formed near the weight attachment position on the joint surface of the brake lining with the rim, it is possible to prevent the heat generated in the brake lining from being directly transmitted.

If a weight is attached to the inner surface of the rim or the side of the web via an elastic body, the cover can be covered, and even if frictional powder accompanying braking is generated, it will accumulate around the 3 simple bodies and the weight. Can be prevented.

The inventor of the present application has analyzed data based on actual measurements, succeeded in formulating the effective range of the proposed technology into a mathematical expression, and confirmed that extremely effective measures can be taken within that range. This formula will be described later in detail.

Drum brakes are braked by friction between the inner peripheral surface of the brake drum and the outer peripheral surface of the brake lining. Therefore, the rim that fixes the brake lining and the web that supports the rim become hot due to the heat generated during braking, and the elastic body and the weight attached to the rim or the web are also affected by the heat. Since the weight and the elastic body, and the elastic body and the web or rim are fixed by bonding, the adhesive is also affected by heat.

This prevents the elastic body and the adhesive from deteriorating, and further reduces the vibration damping function of the elastic body when abrasion powder of the brake lining generated during braking is accumulated. Practically, even if the weight is fixed to the web or rim via an elastic body, it can be sufficiently provided in a flat state, and by providing the weight and the elastic body with a rod and a rod, the elasticity and the adhesive can be reduced. It can be seen that deterioration and deterioration of the vibration damping function of the elastic body can be suppressed, confirming that this can improve reliability. Was.

A second aspect of the present invention is a drum brake, wherein a weight is attached to a back plate of the drum brake via an elastic body. The elastic body and the weight can be directly attached to the back plate. In this case, too, it is effective to erect a rod and attach the weight to the rod via the elastic body. Fixing with bolts instead of rods is also effective as a practical structure.

The above mathematical expression will be described. This formula is the same for both the brake plate and the back plate.

When the mass of the weight is m and the panel constant of the elastic body set between the weight and the vibrating member (brake shoe, back plate, etc.) is k, the specific weight of the weight mounted via the elastic body The vibration frequency is

f. = (1 / (2 7Γ)) (k / m)

Becomes Experimental studies have confirmed that it is effective to set this natural vibration frequency almost equal to or lower than the frequency of the main component of the squeal frequency f _s by the brake shoe. For example, the natural vibration frequency f. The relationship between the squeal frequency f «and

f «> 2 f 0

Is effective over a wide frequency range of the squeal frequency f ,.

Conversely, if the squeal frequency f, becomes a substantially constant frequency due to the structure of the brake, the weight m of the weight is reduced and the natural vibration frequency f is increased. It was also found that the design could be made closer to the resonance frequency f, so that the weight of the device could be reduced.

That is, to set the mass m of the weight small,

f «0

As a result, it was found that the vibration of frequency f, was effectively absorbed. In other words, the squeal frequency can be treated as an almost constant value depending on the shape of the rim.In this case, the squeal frequency f, due to the brake is almost equal to, or slightly vice versa,

f _s <fo

It turned out that it was effective even if it happened.

A third aspect of the present invention is characterized in that a weight is attached to a wheel cylinder of a drum brake via an elastic body. The wheel cylinder is a member for receiving the braking hydraulic pressure and transmitting the braking hydraulic pressure to the spider via a pair of pistons housed therein. The wheel cylinder itself is mounted inside the back plate of the drum brake. The wheel cylinder receives the vibration of the brake shoe generated at the time of braking, and transmits this vibration to the back plate to be a factor that increases brake squeal. Therefore, by attaching a weight to the outer periphery of the wheel cylinder via an elastic body, the vibration can be suppressed, and it has been experimentally confirmed that the above formulas are common.

If these are repeated and explained qualitatively, when a vibrating member (in this case, a brake shoe, a back plate of a drum brake, or a wheel cylinder) vibrates, a weight is attached to the vibrating member via an elastic body. At low frequencies, the weight oscillates at the same phase as the vibrating member, but as the frequency increases, the vibration phase of the weight deviates from the vibration phase of the vibrating member. When the frequency exceeds a certain frequency, the vibration phase becomes opposite phase, that is, 180 degrees different. This means that the elastic body is deformed to convert vibration energy into heat energy, thereby suppressing vibration of the vibration member. In other words, it is only necessary to set a frequency at which acoustic noise remarkably occurs at a frequency at which the weight vibration has an opposite phase so as to suppress the vibration. Furthermore, the number of weights is not one, and a plurality of weights can be attached to the inside of the rim or the web via the elastic body, respectively. It is also effective to slightly change the natural vibration frequency of a plurality of weights when the squeal frequency covers a wide range. The panel constant of an elastic body is determined by the properties of the material of the elastic body and its shape. A heat-resistant rubber or other plastic material is convenient as the material of the elastic body, and its shape should be set theoretically and experimentally so as to satisfy the above equation. Good.

The inventor of the present application has repeated experiments under various conditions, and has experimentally confirmed that the noise of the brakes generated during braking of the vehicle can be effectively reduced. We have repeatedly confirmed that if the above-mentioned weight was attached to the brake shoe with a structure that generates squeal through an elastic body, the squeal would be significantly reduced, and if it was removed, squeal would occur.

Since the elastic body and the weight are inexpensive parts having a simple structure, the brake squeal can be reduced to a practically sufficient level by the present invention without much expense. Even if the brake lining is replaced, its performance does not change. In a more specific embodiment, the brake squeal frequency is generally not a uniform frequency but a mixture of a plurality of frequencies. However, actual measurements include many frequency components exceeding approximately 1 kHz. More specifically, frequency components in the range of 1.4 kHz to 2 kHz are harsh sounds.

Therefore, the natural vibration frequency f of the weight attached via the elastic body. Is preferably set to around 1 kHz or smaller. When this was changed under various conditions and confirmed experimentally, the natural vibration frequency f was found. It can be seen that setting to about 500 Hz is effective over a wide frequency range, and further reducing the natural vibration frequency f. It was confirmed that setting the frequency to 100 Hz is effective for reducing the squeal in a wider frequency range. Furthermore, this natural vibration frequency f. Although it is conceivable to make the elastic material smaller, in reality, the elastic material becomes softer and the mass of the weight increases, so whether it is industrially effective and whether a good elastic material can be obtained at low cost Problems arise.

On the other hand, the rim is a member that generates heat due to the friction between the brake drum and the brake lining, so it is necessary to select an elastic material that has appropriate heat resistance and durability. From this element, the natural oscillation frequency ¾l¾ f. Choosing an extremely small value has a difficult problem. In this experiment, a synthetic rubber (or plastic material) having various elastic coefficients was selected as the elastic material, and a metal material (specific In general, lead was used.

Based on these considerations, it is possible to select an appropriate synthetic rubber (or plastic material) with excellent heat resistance, and to reduce the mass of the weight to a practically convenient several hundred grams. , Natural frequency f. However, it is considered industrially superior to set the frequency around 100 Hz, or a little higher around 200 Hz.

[Brief description of drawings]

FIG. 1 is a partial side view showing the configuration of the first embodiment of the present invention.

FIG. 2 is a perspective view showing the configuration of the first embodiment of the present invention.

FIGS. 3 (a) and 3 (b) are diagrams showing measured values of the vibration frequency and the braking sound level during braking in the first embodiment of the present invention and the conventional example.

FIG. 4 is a perspective view showing an external shape of a test sample according to the first embodiment of the present invention.

FIGS. 5 (a) and 5 (b) are diagrams showing the results of a vibration damping test of the first embodiment of the present invention and the conventional example.

FIG. 6 (a) is a diagram showing the vibration damping state before the thermal deterioration test in the first embodiment of the present invention, and FIGS. 6 (b) to (g) are the vibration damping states after the heat deterioration test in the first embodiment of the present invention. FIG. 1 (i) is a diagram showing a vibration decay state in a conventional example.

FIG. 7A is a schematic diagram showing the structure of the first embodiment of the present invention, and FIG. 7B is a schematic diagram showing a state when it is subjected to vibration.

Fig. 8 (a) is a schematic diagram showing another type of vibration energy absorption structure, and (b) is a schematic diagram showing a state when it is subjected to vibration.

FIG. 9 is a partial side view showing a state in which the elastic body and the weight according to the second embodiment of the present invention are attached to the inner surface of the rim.

FIG. 10 is a view on arrow A shown in FIG. 9 in the second embodiment of the present invention.

FIG. 11 is a perspective view showing a state in which the elastic body and the weight according to the second embodiment of the present invention are attached to the inner surface of the rim.

FIGS. 12 (a) and 12 (b) show the appearance of the sample in the second embodiment of the present invention. FIG.

FIGS. 13 (a) and 13 (b) show the results of the impact test in the second embodiment of the present invention.

FIGS. 14 (a) and (b) are diagrams showing the results of the impact test in the second embodiment of the present invention and the conventional example.

FIGS. 15 (a) and 15 (b) are views showing the results of a hit test in the second embodiment of the present invention and the conventional example.

FIG. 16 is a partial side view showing the configuration of the third embodiment of the present invention.

FIG. 17 is a partial sectional view in the direction of arrow B shown in FIG. 16 when the weight and the elastic body in the third embodiment of the present invention are attached to both sides of the web.

FIG. 18 is a partial sectional view in the direction of arrow B shown in FIG. 16 when the weight and the elastic body according to the third embodiment of the present invention are attached to one side of the web.

FIG. 19 is a circumferential sectional view of a brake shoe showing a configuration of a fourth embodiment of the present invention. FIG. 20 is a partial side view showing the configuration of the fifth embodiment of the present invention.

FIG. 21 is a partial plan view showing the configuration of the fifth embodiment of the present invention.

FIG. 22 is a sectional view of a drum brake showing a configuration of a main part of a sixth embodiment of the present invention. FIG. 23 is a view for explaining an experimental sample in the sixth embodiment of the present invention.

FIG. 24 is a diagram showing a braking noise level for each traveling distance in the sixth embodiment of the present invention. FIG. 25 is a diagram showing an example of actual recording of the braking noise level with respect to the frequency in the sixth embodiment of the present invention.

FIG. 26 is a front view of the inside of the drum brake showing the configuration of the seventh embodiment of the present invention.

Fig. 27 is a diagram illustrating the deformation of the brake shoe when brake squeal occurs during braking.

[Best mode for carrying out the invention]

Next, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)

FIG. 1 is a partial side view showing the structure of the first embodiment of the present invention, and FIG. It is a perspective view which shows a structure.

In the first embodiment of the present invention, a hollow cylindrical rod 6a is erected on an inner surface of a rim 3 on which a brake lining 2 which is pressed against a brake drum 1 and generates a braking force by frictional resistance is mounted. The weight 5a is attached to the ring via the elastic body 4a of the ring. When the mass of the weight 5 a is m and the panel constant of the elastic body 4 a is k, the natural vibration frequency of the weight 5 a attached via the elastic body 4 a

f. = (1 / (2ττ)) (k / m)

Is set to be lower than the squeal frequency f of the brake lining 2. Here, test results according to the first embodiment of the present invention configured as described above will be described.

(Test 1-1)

First, the results of measuring and recording the sound of brake squeals on a medium-sized bus will be explained.

Figures 3 (a) and 3 (b) show a microphone placed near the brake of the vehicle under test, take out the sound generated from the brake as an electric signal, amplify it with a wideband sound signal amplifier, and Is the frequency component of the spectrum analyzed by a spectrum analyzer. The horizontal axis is frequency, and the vertical axis is sound level in dB. The vertical axis is the relative value. FIG. 3 (a) shows a measurement result of the brake according to the present invention, and FIG. 3 (b) shows a comparative example. This comparative example shows the result of the same measurement with the same brake device and the same vehicle, but with the weight and the elastic body, which are the elements of the present invention, simply removed. This test is the result of an actual vehicle test on a medium-sized bus, and no simulated elements are included in this test.

That is, as shown in Fig. 3 (b), during the actual test of a medium-sized bus, the rear wheel brakes showed a high peak near the frequency of about 1.5 kHz, a small peak at 2.25 kHz, and a moderate peak at 3 kHz. At the peak, there was a brake squeal that concentrated the sound energy. As a countermeasure, as shown in Fig. 4, the test was performed by attaching four sets (eight sets per wheel) of weight to one rim 3 via an elastic body. As a result, Fig. 3 (a) As shown in the above, the brake squeal that occurred due to high level and level peak disappeared,

The brake sound level was less than 30 dB over the entire measurement range up to 4 kHz. This level is a one-shot noise level, and gives the human ear the impression that the brake squeal has disappeared.

(Test 1-2)

Further, a vibration damping test was performed before and after the weight of the example of the present invention was mounted. In this test, the brake (approximately ² mZs ec ² : 0.2 g at deceleration) was applied to the wheel cylinder using the brake device of a medium-sized bus, and the wheel cylinder was subjected to a pressure (30 kgZcm ² ). Was measured by hitting with a hammer to which a certain pressure was applied and measuring the vibration. The results are shown in Figs. 5 (a) and (b). In Fig. 5, the horizontal axis is the time axis, and the vertical axis is the amplitude of the acoustic vibration.

FIG. 5 (a) shows the vibration attenuation characteristics when the weight embodying the present invention is mounted as shown in FIG. 4, and FIG. 5 (b) is a comparative example. In this comparative example, the measurement was performed with the same apparatus simply removing the weight and the elastic body. Figure 5 shows the waveforms obtained by converting acoustic vibrations into electrical signals by pickup, amplifying the electrical signals by a broadband amplifier, and observing them with an oscilloscope. The horizontal axis represents time and the vertical axis represents vibration amplitude. From these results, it is understood that the acoustic vibration is significantly reduced by implementing the present invention.

(Test 1-3)

Next, a deterioration test for a practical device will be described.

A thermal degradation test was performed on the first embodiment of the present invention (FIG. 1). This is mounted on an actual vehicle and travels on a standard travel path for thermal evaluation (typically equivalent to a steep slope in Japan). The temperature of the brake shoe is measured and acceleration test conditions are determined based on the temperature change. It is set. On the basis of the acceleration test conditions, the brake shoe of the present invention was placed in a thermostat and subjected to repeated temperature cycling to forcibly degrade, and then subjected to a vibration damping test.

Fig. 6 shows the test results, and Fig. 6 (a) shows the results of the new product before the thermal degradation test. Figures (b) to (g) show the results after a thermal degradation test corresponding to 8,000 to 800,000 km, respectively, and Figure (h) shows the structure of the present invention in an actual vehicle. The result after running 4,000 km (maximum temperature of 200 ^βして) is shown in the figure. (I) is a comparative example, in which the present invention is not implemented, that is, the weight and the elastic body are shown. From these results, the results of the test in the state in which the vehicle was removed can be assured, and the life of the structure of the present invention can be assured as the life of the vehicle, and the secular vibration damping property is almost the same as that of a new vehicle. It turned out to be the same.

Next, the vibration mode of the first embodiment of the present invention will be described.

FIG. 7 is a schematic diagram showing a structure of the first embodiment of the present invention, and FIG. 8 is a schematic diagram showing a vibration energy absorbing structure of a structure using a conventionally known steel plate. 7A and 8A show the state before receiving the vibration, and FIG. 7B shows the state before receiving the vibration. In the structure of the first embodiment of the present invention shown in FIG. 7, the rod 6a is erected on the inner surface of the rim 3, and the weight 5a is attached to the rod 6a via the elastic body 4a. As a result, the vibration generated at the rim 3 is transmitted to the rod 6a, and the weight 5a is greatly deformed up and down via the elastic body 4a as shown in FIG. 3 (b), and the vibration energy becomes heat energy. Is dissipated. In the structure using the steel sheet shown in FIG. 8, an elastic body 12 is disposed between the two steel sheets 11, and when subjected to vibration, the steel sheet 11 is deformed as shown in FIG. Converts vibration energy to heat energy. When this is compared with the structure of the first embodiment of the present invention, it can be seen that the deformation of the elastic body 4a is larger than the deformation of the elastic body 12 and the vibration energy is efficiently absorbed.

(Second embodiment)

FIG. 9 is a partial view showing a state in which the elastic body and the weight according to the second embodiment of the present invention are attached to the inner surface of the rim. FIG. 10 is a view taken in the direction of the arrow shown in FIG. FIG. 1 is a perspective view of a second embodiment of the present invention.

In the second embodiment of the present invention, a plurality of weights 5b are provided on the inner surface of a rim 3 on which a brake lining 2 which is pressed against a brake drum 1 and generates a braking force by frictional resistance is provided via an elastic body 4b. It is a structure attached by adhesion. here, When the mass of weight 5 b is m and the panel constant of elastic body 4 is k, the natural frequency of weight 5 attached via elastic body 4

f 0 = (1 / (2)) ^ (k / m)

Is set to be lower than the squeal frequency f of the brake lining 2. The elastic body 4b and the weight 5b are fixed with an adhesive.

Next, test results in the second embodiment of the present invention configured as described above will be described.

(Test 2-1)

Fig. 12 shows the shapes of the weight 5b and the elastic body 4b used in the test. Here, the combination of the weight 5 b and the elastic body 4 b is referred to as a “sample”. Fig. 12 (a) shows the structure of sample (1), and Fig. 12 (b) shows the structure of sample (2). The weight material was lead, and nitrile rubber with a hardness of 60 degrees was used for the elastic body. Sample (1) is large and has a weight of 6 Omm x 28 mm x 1 Omm and a weight of 300 g. The size of the elastic body is 6 Omm x 28 mm x 5 mm. Sample (2) is small, has a weight of 27 mm x 22 mm x 1 Omm, and weighs 100 g. The size of the elastic body is 7mm X 22mm x 5mm. Many samples (1) and (2) as described above were prepared. First, FIG. 13 is a diagram showing the test results of the sample alone before the sample was bonded to the brake shoe. Fig. 13 (a) shows the test results for sample (1), and Fig. 13 (b) shows the test results for sample (2). The test using this sample alone was performed as follows. In this test, a sample (1) and a sample (2) were taken, one at a time, individually attached to a large surface plate, and a shock was applied to the vicinity of the plate with a hammer. Attach pickups (sound converters) to the sam- ble and surface plate, respectively, and extract acoustic vibrations as electrical signals. Each of these electric signals was amplified by a broadband amplifier and subjected to frequency analysis by a two-channel spectrum analyzer to record the vibration amplitude of the weight and the phase difference between the vibration of the weight and the vibration of the surface plate. Figure 13 shows the frequency on the horizontal axis and the frequency on the vertical axis FIG. The amplitude is a logarithmic scale and a relative value. The unit of the phase difference is degrees.

Looking at the test results shown in Fig. 13, in Fig. 13 (a), it can be seen that the vibration of the weight has a large amplitude near 100 Hz and gradually decreases at higher frequencies. Understand. The phase difference between the vibration applied to the surface plate and the vibration of the weight is almost equal in the low frequency region, but a phase delay is seen corresponding to the amplitude peak near 20 OHz, and the frequency is further increased. As the phase becomes larger, the phase difference becomes almost 180 degrees above 100 OHz, and the vibration of the weight becomes the opposite phase of the vibration applied to the surface plate. You can see that. The test results show that the vibration of the weight suppresses the applied vibration. In Fig. 13 (b), too, it can be seen from the fact that the mass of the weight is small, that the frequency with a large amplitude is slightly lower, and that the frequency at which the phase is reversed is also lower.

Based on these test results, when a part like this sample (1) or (2) is mounted on a brake, the phase of the vibration will be out of phase in the frequency domain where the vibration of the weight exceeds 100 OHz or 800 OHz. It can be seen that the vibration of the weight acts to suppress the vibration of the brake.

(Test 2-2)

Next, the test results for each brake shoe will be described.

As shown in Figs. 9 to 11, the above samples were mounted on a brake shoe and tested. Figure 14 shows the test results. Fig. 14 is a diagram in which the brake shoe was placed on a sponge and a single impact was applied with a hammer to record the damping state of the vibration amplitude. In other words, a pickup was attached to the brake, the vibration was extracted as an electric signal, and the electric signal was amplified by a broadband amplifier and observed with an oscilloscope. In FIG. 14, the horizontal axis represents time, and the vertical axis represents the relative value of the amplitude.

FIG. 14A shows the test result of the second embodiment of the present invention (FIG. 11), and FIG. 14B shows a comparative example. This comparative example is a test result obtained by performing the same measurement with the sample removed from the brake shoe of the second embodiment of the present invention. From Figure 14 In the example of the present invention, it can be seen that the vibration does not continue after the impact is applied, and the vibration is immediately absorbed and attenuated. That is, it can be seen that the present invention effectively absorbs the vibration of the brake shoe. In the case of Fig. 14 (a) and the case of (b), it can be seen that the sound response is clearly different even when a person listens to the ear.

(Test 2-3)

Next, a test on a practical vehicle will be described with reference to FIG.

As shown in Fig. 11, one brake with a weight of 300 g, two weights with a weight of 200 g, and one weight with a weight of 100 g were attached to the brake shoe mounted on the vehicle, as shown in Fig. 11. The test was performed by fixing the vehicle with an elastic body in between and parking the vehicle in a fixed place. Set the vehicle with the brake applied, attach the pick-up to the brake drum, extract the acoustic signal as an electric signal, amplify it with an amplifier, and watch the electric signal with a sampling oscilloscope! did. Fig. 15 shows the vibration damping waveform of a single hit of the brake drum with a hammer.

When the weight and the elastic body were not attached, vibration with large amplitude and its lingering occurred as shown in Fig. 15 (b), but when the weight and the elastic body were attached, as shown in Fig. 15 (a). The amplitude appeared to be small, indicating that the vibration during braking was absorbed.

(Test 2-4)

Next, a test was performed by running the above-mentioned practical vehicle. When the weight and the elastic body according to the second embodiment of the present invention were all removed and the vehicle was run and the brake was applied, a loud squeal was generated. However, it was confirmed that the squeal was not generated at all if the above measures were taken. This was confirmed under various driving conditions and various braking conditions. It was also confirmed that brake squealing occurred when the lid of the weight and elastic body was removed.

As can be seen from these experimental results, the mounting of the weight 5b via the elastic body 4b absorbs the vibration generated during braking and reduces the occurrence of brake squeal to a practically sufficient level. all right.

In the second embodiment described above, the weight and the elastic body are fixed by an adhesive. Was. Although the strength is practically sufficient even if fixed with an adhesive, mechanical fixing parts can be used to further secure the attachment. An example of the fixing component can be a structure that penetrates the weight 5b, the elastic body 4b, and the rim 3 using a bolt or a pin. In this case, it is preferable to provide a concave portion (a concave portion corresponding to the concave portion 13 in FIG. 19) on the surface of the brake lining near the portion using the fixing component.

(Third embodiment)

FIG. 16 is a partial side view showing the configuration of the third embodiment of the present invention, and FIG. 17 is the direction of the arrow B shown in FIG. 16 when weights and elastic bodies according to the third embodiment of the present invention are attached to both sides of the web. FIG. 18 is a partial sectional view in the direction of the arrow B shown in FIG. 16 when the weight and the elastic body according to the third embodiment of the present invention are attached to one side of the web.

In the third embodiment of the present invention, a through hole is provided in the web 3a, and a bush 17 is passed through the pin 16a or 16b passed through the through hole. The elastic body 4c contained in the ring-shaped weight 5c is fixed. The elastic body 4 c and the weight 5 c are arranged on both sides of the web 3 a as shown in FIG. 17 as shown in FIG. 17, or are arranged on one side of the web 3 a as shown in FIG. 18, One ends of the pins 16a and 16b are caulked and fixed. Spaces are provided on both sides of the weight 5c and the elastic body 4c so that they do not contact the side surface of the web 3a and the end surface of the pin 16a due to vibration.

This structure is simple and reliable for mounting the weight and elastic body, and is a practically excellent structure. It was confirmed that this structure also reduced brake squeal.

(Fourth embodiment)

FIG. 19 is a circumferential sectional view of a brake shoe showing a configuration of a fourth embodiment of the present invention.

In the fourth embodiment of the present invention, a rod 6b is erected on the top of the web 3a, and a recess 13 is provided at a position corresponding to the rod 6b of the brake lining 2. The fourth embodiment also absorbs the vibration caused by the deformation of the rim 3 generated during braking and generates the brake squeal as described above. It can be reduced as in the embodiment.

(Fifth embodiment)

FIG. 20 is a partial side view showing the configuration of the fifth embodiment of the present invention, and FIG. 21 is a partial plan view showing the configuration of the fifth embodiment of the present invention.

In the fifth embodiment of the present invention, both sides of a web 3a supporting a rim 3 on which a brake lining 2 which is pressed against a brake drum 1 and generates a braking force by frictional resistance is mounted via elastic bodies 4e. A plurality of weights 5e are attached by adhesion, and a cover 20 is provided around the elastic body 4e and the weights 5e to provide a space sufficient for free vibration and to hermetically seal. Due to the cover 20, abrasion powder generated by abrasion of the lining does not directly adhere to the weight 5 and the elastic body 4e, and does not change its mass or elastic characteristics.

(Sixth embodiment)

FIG. 22 is a sectional view of a drum brake showing a configuration of a main part of a sixth embodiment of the present invention. In the sixth embodiment of the present invention, a weight 5f is attached to the surface of the back plate 21 via an elastic body 4f. In the sixth embodiment, the resonance of the back plate 21 due to the vibration generated at the time of braking is prevented, whereby the brake squeal can be suppressed as in the above-described embodiments. In FIG. 22, the elastic body 4 f is bonded to the back plate 21, but the rod or the bolt is pierced at the position indicated by the dashed line in FIG. The falling off of the elastic body 5 f can be reliably prevented.

(Test 3)

As shown in Fig. 23, weights 5f were attached to the eight positions PI to P8 on the surface of the back plate 21 via elastic bodies 4f, and the vehicle was mounted on a small bus where brake squealing occurred, and an actual vehicle test was performed. Was. As a result, it was demonstrated that the level of about 120 dB (A) at a position 1 m from the brake was reduced to 80 dB (A) or less, which is a level that does not matter for practical use.

FIG. 24 shows the braking noise level for each traveling distance in the sixth embodiment of the present invention. Things. This is done by installing a new brake on a medium-sized bus, running for about 500 km, and when the brake squealing occurs, eight weights 5 f are attached to the back plate 21 of one wheel via the elastic body 4 f described above. The vehicle was mounted, and a running test of about 400 km was repeated. During this running test, microphones were installed 1 m behind the left and right wheels, and a vibration acceleration pickup was attached to the back plate 21 to observe the occurrence of brake squeal on the left and right wheels. As a result, as shown in Fig. 24, the wheel without the elastic body 4 f and the weight 5 f generated a brake squeal of up to 120 dB, but the mounted wheel had a background noise level of 80 dB. d Always below B, no brake squeal occurred.

FIG. 25 is a diagram in which the braking sound in the sixth embodiment of the present invention is measured by a simple-type in-vehicle spectrum analyzer. The horizontal axis indicates frequency, and the vertical axis indicates noise level on a logarithmic scale. In the state before implementing the present invention, brake noise was observed at the braking frequency of 660 Hz, but by attaching the weight 5 f to the back plate 21 via the elastic body 4 f, The braking sound level decreased to the position indicated by the middle X, and the occurrence of squeal was suppressed. This was clearly observed by human ears.

As described above, according to the present invention, it is possible to reduce the noise of the brake generated when the vehicle is braked in the most effective form only by adding inexpensive parts. In particular, the size of the brake shoe 18 is large, and its effect is great when applied to large vehicles.Continuing to reduce squeal without changing the performance even if the brake lining is replaced Can be.

Furthermore, since the elastic body and the weight are covered by the cover, wear powder of the brake lining generated at the time of braking is prevented from being deposited therearound, and the elastic body and the adhesive are degraded, and the elastic body has a cushioning function. The decline can be suppressed, and the reliability can be further improved.

(Seventh embodiment)

FIG. 26 is a front view of the inside of the drum brake showing the configuration of the seventh embodiment of the present invention. In the seventh embodiment of the present invention, the brake drum 1 is pressed against the inner surface of the brake drum 1. A brake lining 2 that applies a braking force by friction when pressed, a pair of brake shoes 18 on which the brake lining 2 is mounted on the outer periphery, and one end of each of the brake shoes 18 is rotatably supported. 22 and a wheel cylinder 23 that applies pressing force to the other end of each brake shoe, and a back plate that covers the opening of the brake drum 1 and supports the spider 22 and the wheel cylinder 23 (Not shown), and a weight 5 h is attached to the outer periphery of the wheel cylinder 23 via an elastic body 4 h. Also in the case of the seventh embodiment, when the mass of the weight 5 h is m and the panel constant of the elastic body 4 h is k, the natural vibration frequency of the weight 5 h attached via the elastic body 4 h is also

f 0 = (1 / (2? r)) ^ (kZm)

Is set to be lower than the squeal frequency f of the brake lining 2. Also in the seventh embodiment, since the weight 5 h is attached to the wheel cylinder 23 via the elastic body 4 h, the vibration generated at the time of braking is absorbed, and the generation of brake noise is practically sufficient. To be reduced. Furthermore, since the elastic member 4 h and the weight 5 h are attached to the wheel cylinder 23 which does not directly receive the heat generated, the deterioration of the elastic member 4 h and the adhesive is prevented from being stopped.

Claims

The scope of the claims

1. A brake shoe characterized in that a weight is attached via an elastic body to a rim to which a brake lining is attached.

2. The brake shoe according to claim 1, wherein a rod is erected on the rim, and the weight is attached to the rod via the elastic body.

3. The brake shoe according to claim 1, wherein the position where the weight is attached is an inner surface of the rim.

4. The brake shoe according to claim 1, wherein a position where the weight is attached is a web of the rim.

5. The shaker according to claim 4, wherein the position where the weight is attached is a side surface of the web.

6. The brush as claimed in claim 4, wherein the position where the weight is attached is at the top of the web.

7. When the mass of the weight is m and the panel constant of the elastic body is k,

Natural vibration frequency of the weight attached via the elastic body

f 0 = (1 (2 7Γ)) (k / m)

Squeal frequency f but by the brake shoe and foremost, nearly equal or a squeal frequency f, more claims 1 was set low to 6 les, brake shoe one _c according to whether the deviation

8. The elastic body has a ring shape, and the rod penetrates the center of the elastic body, the rod is made of metal, and a ring-shaped weight is provided so as to include the elastic body. The brake shoe according to claim 2 or any one of claims 3 to 7 according to claim 2.

9. The brake shoe according to claim 8, wherein the rod has a cylindrical shape or a cylindrical shape.

10. A support is attached to the rod, and at least a space is provided between the support and the rod, and the elastic body is provided so as to include the support. 10. The brake according to claim 8, wherein a ring-shaped weight is provided so as to include the elastic body.

11. The brake shoe according to claim 1, wherein a recess is formed near a mounting position of the weight on a joint surface of the brake lining with the rim.

12. The brake shoe according to any one of claims 1 to 11, wherein the weight and the elastic body are covered with a cover.

1 3. A drum brake provided with the brake shoe according to any one of claims 1 to 12.

1 4. Drum brake characterized in that a weight is attached to the back plate via an elastic body.

1 5. When the mass of the weight is m and the spring constant of the elastic body is k,

Natural vibration frequency of the weight attached via the elastic body

f 0 = (1Z (27Γ)) (k / m)

There approximately equal or a squeal frequency f, lower set claims 1 4 drum brake according the squeal frequency f _s by the brake shoe scratch.

16. The drum brake according to claim 14, wherein a rod is erected on the back plate, and the weight is attached to the rod via the elastic body.

17. The drum brake according to claim 15, wherein the weight and the elastic body are attached to the back plate by a rod or a bolt.

1 8. A drum brake characterized in that a weight is attached to the wheel cylinder via an elastic body.

1 9. When the mass of the weight is m and the panel constant of the elastic body is k, the natural vibration frequency of the weight attached via the elastic body

f 0 = (1 / (2ττ)) ^ k / m)

The drum brake according to claim 18, wherein is set to be approximately equal to or lower than the squeal frequency f, of the brake shoe.